Air and fuel mixing and feed system

ABSTRACT

An air and fuel mixing and feed system for an internal combusion engine equipped with throttle valve means and an induction manifold includes: venturi and duct means communicating with ambient air, with a bath of liquid fuel in reservoir means, and with said throttle valve means, and comprising venturi means for developing static pressure in a region therein varying inversely in intensity with velocity of engine intake air flow; and means for pumping liquid fuel and regulating liquid fuel flow and pressure, comprising, pump means operated at a rate increasing and decreasing with engine operating speed, and fuel flow regulator means including pressure responsive flow control valve means having an excess pressure-alleviated pressure chamber communicating with said region and with a liquid fuel pressurizing chamber in said pump means, for said pressure responsive flow control valve means to open in response to decreased static pressure in said region for supplying said reservoir means with liquid fuel received from said pressurizing chamber of said pump means, and for said pressure responsive flow control valve means substantially to close to relatively high static pressure in said pressure chamber.

United States Patent [191 Wooldridge Apr. 1,1975

[ AIR AND FUEL MIXING AND FEED SYSTEM [75] Inventor: Bobby M.Wooldridge, College Park, Ga.

[73] Assignee: Lynwood A. Maddox, Decatur, Ga.

[22] Filed: Feb. 14, 1974 [21] Appl. No.: 442,425

2,852,011 9/1958 Pringham..... 3,013,545 12/1961 Nostz 123/139 AW123/139 AW 3,713,429 11/1971 Dwyre 123/134 FOREIGN PATENTS ORAPPLICATIONS 655,909 8/1959 Canada 123/139 AW Prinulry E.\'uminerCharlesJ. Myhre Assistant E.\'unzinorR. H. Lazarus Attorney, Agent, orFirm-John B. Armentrout [5 7] ABSTRACT An air and fuel mixing and feedsystem for an internal combusion engine equipped with throttle valvemeans and an induction manifold includes: venturi and duct meanscommunicating with ambient air, with a bath of liquid fuel in reservoirmeans, and with said throttle valve means, and comprising venturi meansfor developing static pressure in a region therein varying inversely inintensity with velocity of engine intake air flow; and means forpumping; liquid fuel and regulating liquid fuel flow and pressure,comprising, pump means operated at a rate increasing and decreasing withengine operating speed, and fuel flow regulator means including pressureresponsive flow control valve means having an excess pressure-alleviatedpressure chamber communicating with said region and with a liquid fuelpressurizing chamber in said pump means, for said pressure responsiveflow control valve means to open in response to decreased staticpressure in said region for supplying said reservoir means with liquidfuel received from said pressurizing chamber of said pump means, and forsaid pressure responsive flow control valve means substantially to closeto relatively high static pressure in said pressure chamber.

15 Claims, 4 Drawing Figures minnow 1:975 #4874 352 SiiiET 1 BF 2 n x 1AIR ANI) FUEL MIXING AND FE EI) SYSTEM This invention relates to gas andfuel mixing and feeding apparatus wherein a both of liquid fuel isutilized for contributing fuel to the gas, and the invention isparticularly directed to improvements in a system for supplying amixture of fuel and air to an internal combustion engine.

An object of the present invention is to provide new and usefulimprovements in an air and fuel mixing and feed system for an internalcombustion engine using a bath of liquid fuel for contributing liquidfuel to the air.

Another object herein is to provide a fuel and air mixing and feedsystem for an internal combustion engine, having air induced to flowthrough a bath of liquid fuel in response to intake of the engine, andto achieve feed of liquid fuel in replenishment of the bath through useof pressure responsive flow control valve means supplied from fuel pumpmeans and by controlling the pressure responsive flow control valvemeans in accordance with static pressure developed within an open regioninside a venturi means and varying in proportion to operating speed ofthe engine, to have fuel delivered from the pump means pass through thepressure responsive flow control valve means and to the bath when thepressure responsive flow control valve means is open in response to lowstatic pressure in the open re gion inside the venturi means, and tohave the pressure responsive flow control valve means substantiallyclose to fuel from the pump means when static pressure in the openregion inside the venturi means has suffi eiently increased.

Another object herein is the provision of a system of the characterindicated wherein replenishment of the bath of liquid fuel further ishad through pressure responsive flow control second valve means suppliedfrom the fuel pump means and by controlling the pressure responsive flowcontrol second valve means to open for fuel delivered from the pumpmeans to pass through the pressure responsive flow control second valvemeans in response to low pressure developed between the throttle valvemeans and the engine when the throttle valve means is in a relativelyclosed position, and which pressure responsive flow control second valvemeans substantially closes in response to rela tively high pressuredeveloped between the throttle valve means and the engine correspondingto when the throttle valve means is in a relatively open position.

A further object herein is the provision of a system ofthe characterindicated, introducing features relating to extracting liquid fuel froman air and fuel mixture en route to an internal combustion engine from abath of liquid fuel.

Other objects in part will be obvious and in part pointed out more fullyhereinafter.

The present invention will be more readily understood from a reading ofthe following specification and by reference to the accompanyingdrawings forming a part thereof. wherein an example of the invention isshown and wherein:

FIG. I is a schematic representation of an air and fuel mixing and feedsystem, partially in vertical sectional view, for an internal combustionengine;

FIG. 2 is a horizontal sectional view taken through a liquid fuelextracting first stage at 22 in FIG. 1;

FIG. 3 is a horizontal sectional view taken at 3-3 through a liquid fuelextracting second stage in FIG. I: and

FIG. 4 is a vertical sectional view taken at 44 in FIG. I through theliquid fuel extracting second stage.

Referring now more particularly to the embodiment of the inventionrepresented in the accompanying drawings. an air and fuel mixing andfeed system, designated in general by the reference numeral in FIG. I,is provided and includes an air and fuel mixing and liquid fuelextracting unit 11 in which a housing I2 forms inside at a lower bottomportion I811 thereof and at adjacent portions ofthe sidewall structureI9 thereof a reservoir means 15 normally containing a bath of liquidfuel 20, such as gasoline, A normally vertical air inlet duct 14 has apa. ageway 16 therein which communicates at upper air intake end 16awith air ambient to the air and fuel mixing and feed system 10. Thelower discharge end 16b of the passageway 16 is im mersed in the bath ofliquid fuel 20 for air in the passageway 16 to move having ingress intothe bath below the surface of the bath and in order to rise in and carryoff fuel from the bath.

Housing 12 further introduces first and second stage extractor means211: and 21b for liquid fuel to be ex tracted from a mixture of air andfuel passing from the bath of liquid fuel 20 in the reservoir means 15en route to an outlet duct 13. which latter duct is an integralcomponent of the housing 12. Further, in this regard. a firstlabyrinthic stage 21a of the extractor means includes a plurality ofsimilar generally horizontal partitions 23 each having a central opening23a therein receiving the air inlet duct 14.. and each of the partitions23 further is cl'iaracterized by having a set of apertures 23h thereinfor the latter to conduct a mixture of air and fuel. The partitions 23are spaced vertically apart from one another, thus subdividing a spacewithin the housing 12 into liquid fuel extracting chambers 24, 25.. 26,27 and 28 extending above the reservoir means 15 and are walled in bythe housing sidewall structure I9. Chambers 24, 25. 26, 27 andn 28 aresubstantially closed off at the inside surface of the housing sidewallstructure 19 and at the outside surface of the air inlet duct 14 and arepacked with filter material 29 suitable for extracting liquid fuel froma mixture of air and fuel while tolerating flow of the mixture. Further,the sets of apertures 23b are horizontally removed one with reference tothe next for placing the chambers 24. 25, 26, 27 and 28 labyrinthicallyin series with one another and flow through the labyrinth to be mainlygenerally horizontal though vertically stepped and reversing fromchamber to chamber. The lowermost one of the partitions 23 has its setof apertures 23b open directly into space immediately above thereservoir means 15 for air entering the bath of liquid fuel 20 from thedischarge end 1611 of the passageway 16 in the air inlet duct andcarrying fuel from the bath to enter the chamber 24 through that set ofapertures 23b, and the uppermost one of the partitions 23 has its set ofapertures 2312 open from the chamber 28 and directly into a compartment30 in the housing 12 immediately above the latter partition. 1812 Asecond labyrinthic stage 21b of the extractor means is formed in anupper lateral extension of the housing 12 and introduces generallyvertical liquid fuel extracting chambers 32, 33, 34 and 35 between aplurality of substantially upright similar partitions 37 spacedhorizontally apart from one another and alternately having upper andlower sets of apertures 37a therein to introduce a predominantlygenerally vertical flow through each of the chambers 32, 33, 34 and 35in labyrinthic series in the order named, having those chambers closedoff at the top by a generally horizontal wall 38 inside the housing 12and at the bottom by an upper portion 18b of the bottom of the housing12 and further having those same chambers closed off at opposite sidesby upper portions of the housing sidewall structure 19. The inner one ofthe partitions 37 and the corresponding set of apertures 37a therein arein common to the compartment and the extracting chamber 31, and theouter one of the partitions 37 and its set of apertures 37a are incommon to the extracting chamber and an inner end of the air and fueloutlet duct 13 which is a duct having a generally rectangular lateralcross section substantially throughout within the housing 12. Outletduct 13 furthermore communicates with the housing outlet port 43. A topwall 39 of the housing 12 constitutes a portion of the wall of theoutlet 13 as does the generally horizontal wall 38 inside the housingand as does a portion of the sidewall structure 19 of the housing whilethe bottom wall portion 18b closes off the inner end of the duct 13 forthat end to communicate with the fuel extracting chamber 35 directlythrough the apertures 37a in the outermost one of the partitions 37.

Further in the present embodiment the housing 12 comprises sump means 42open to the lower end of each of the fuel extracting chambers 31, 32,33, 34 and 35 and having for bottom the bottom wall portion 18b of thehousing and for sides the inner one of the partitions 37 next to thecompartment 30 and portions of the housing sidewall structure 19 on aremaining three sides. Each one of the liquid fuel extracting chambers31, 32, 33, 34 and 35 is packed with filter material 40 which issuitable for extracting liquid fuel from a mixture of air and fuellabyrinthically flowing through the second labyrinthic stage 21b of theextractor means, and the liquid fuel extracted in the chambers 31, 32,33, 34 and 35, such as that by the filter material 40, is fed into thesump means 42 for being returned to the reservoir means 15 in a mannerto be described more fully hereinafter.

Third stage extractor means 45 also is provided in the presentembodiment and includes a housing or casing 46 which at the bottominside comprises sump means 47. A wall 48 within the casing 46 andleading from the top and opposite sidewalls of the casing forms apartition between a pair of labyrinthically interrelated extractingchambers 50 and 51 which intercommunicate with one another through apassage 49 above the sump means 47 and below the lower end of the wall48. Adjacent to the top thereof the casing 46 has an inlet port 52leading into the extracting chamber 50 and an outlet port 53 leadingfrom the extracting chamber 51, both ofthe latter two chambers beingpacked with a suitable filter material 54 for this filter material toextract liquid fuel from an air and fuel mixture passing from the inletport 52 en route to the outlet port 53, and the chambers 50 and 51 arearranged for liquid fuel thus extracted in those chambers to pass intothe sump means 47.

The fuel and air outlet duct 13 has output from the housing outlet 43through an air and fuel outlet extension duct 44 which communicates withthe inlet port 52 in the casing 46 and through the chambers 50 and 51with the outlet port 53, the latter having output through to an air andfuel extension duct 55 and an induction manifold 56 leading into theinternal combustion engine 17. An opening 47:: from the bottom of thesump means 47 communicates for liquid fuel from the sump means47 to bereturned to the reservoir means 15 in a manner hereinafter to be morefully described. A portion 550 of the air and fuel extension duct 55 isbeing a in cross section, and the one-way check valve 59, beingrectangular flapper valve hinged at upper end and inclined leadingdownstream from the hinge in the duct extension 55, has a normallygravity-closed position and is adapted to open in response to flow pastthe one way check valve 59 being induced in the air and fuel mixing andfeed system 10 due to operation of the engine 17. A backfire pressurerelief valve 60 suitably biased to close a port 61 in the portion 55a ofthe air and fuel extension duct 55 is provided having the port 61communicating with the passageway in the duct extension 55 downstream ofthe one-way check valve 59 and is responsive to backfire pressure fromthe engine 17 to open the port 61 to air ambient to the engine, therebyrelieving backfire pressure with the one-way check valve 59 meanwhilebeing closed.

Throttle valve means 62, in the passageway formed by the air and fuelextension duct 55 and the induction manifold 56 downstream of theone-way check valve 59 and the backfire pressure relief valve 60, isused to control operating speed of the engine 17 in accordance withbeing given increasing open positions to increase the engine operatingspeed and reduced open positions to reduce the engine operating speeddown to engine idling speeds. Under all of these conditions of engineoperation, air ambient to the air and fuel mixing and feed system 10, inview of negative pressure transmitted into the induction manifold 56from the engine 17, is induced to enter the upper air intake end 16a ofthe passageway 16 in the air intake duct 14 and be conducted through thepassageway 16 and thence through a bath of liquid fuel 20 normally inthe reservoir means 15, thus carrying off fuel from the bath, and topass through the first liquid fuel extracting stage means 21a and intothe second liquid fuel extracting stage means 21h, the air and fueloutlet duct 13, and through air and fuel outlet duct extension 44 intothe third liquid fuel extracting stage means 45, and thence through theair and fuel outlet duct extension 55 and the induction manifold 56 intothe engine 17. During the flow thus induced, liquid fuel is extracted inthe first liquid fuel extracting stage means 21a and returns through theapertures 23b in the labyrinth partitions 23 to the reservoir means 15by gravity, and further amounts of liquid fuel are extracted from therelatively dry mixture of air and fuel flowing in the second and thirdliquid fuel extracting stage means 21!; and 45 respectively, and liquidfuel extracted passes into the sump means 42 and 47 respectively, thusfor the engine 17 to receive a dry mixture of air and fuel through theinduction manifold 56 under the control of the throttle valve means 62.

For regulating the admission of liquid fuel to replenish the liquid fuelin bath 20, the air and fuel mixing and feed system 10 includes pressureresponsive flow control first and second valve means and 80, the firstvalve 70 having an inlet opening 70a into a liquid fuel chamber 71 fromwhich an outlet opening 70b of the first valve means leads into thepassageway 16 in the air inlet duct means 14. A pressure chamber 72within the first valve means 70 has a wall in the form of a diaphragm 74in common with the liquid fuel chamber 71, and a valve needle 73 havingone end secured to the center of the diaphragm 74 projects within theliquid fuel chamber 71 so as normally to close the valve outlet opening7017 under the bias of a helical spring 75 housed in the pressurechamber 72. Spring 75 is located compressed having its opposite endsrespectively secured to the center of the diaphragm 74 and to theopposite outside end wall of the pressure chamber 72.

A first venturi 90 in the air and fuel mixing and feed system forms acomponent of the air inlet duct means 14 and introduces a constrictedopen region in the passageway 16 downstream from the fuel outlet port7017 in the flow control first valve means 70. A bleed line 76 havingits inner end 760 open within the open region inside the first venturi90 in the passageway 16 communicates with the pressure chamber 72 of theflow control first valve means 70 for the latter means to open theoutlet port 70b to an increasing degree in response to static pressurebeing decreased and transmitted from the region inside the first venturi90 through bleed line 76 into the pressure chamber 72 and be closed byspring 75 in response to relatively high pressure transmitted from theregion inside the first venturi means through bleed line 76 to thepressure chamber 72.

The pressure responsive flow control second valve means 80 is similar tothe flow control first valve means 70 and comprises an inlet opening 80ainto a liquid fuel chamber 81 from which an outlet opening 80b of thesecond valve means communicates with the passageway 16 in the air inletduct means 14 upstream of the first venturi 90. The flow control secondvalve means 80 further has a wall forming a diaphragm 84 which is incommon to the liquid fuel chamber 81 and a pressure chamber 81, andthere is a valve needle 83 secured to the center of the diaphragm 84 inthe liquid fuel chamber 81 and projecting to control the outlet port80h. A helical spring 85 in the pressure chamber 82 is secured at afirst of its opposite ends to the center of diaphragm 84 and at thesecond of its opposite ends to the outside end wall of the pressurechamber 82 opposite the diaphragm 84, the spring 85 normally beingcompressed holding the valve needle 83 in closing position withreference to the valve outlet port 801;. A bleed line 79 having an end79a open into the air and fuel mixture flow path inside the inductionmanifold 56 downstream of the throttle valve means 62 is open atopposite end 79b into the pressure chamber 82 of the pressure responsiveflow control second valve means 80 for the valve needle 85 to open theoutlet port 8012 in response to low pressure developed between thethrottle valve means 62 and the engine 17 having the throttle valvemeans in a relatively closed position and for the second valve means 80to close in response to relatively high pressure developed between thethrottle valve means and the engine when the throttle valve means is ina relatively open position.

Pump means in the air and fuel mixing and feed sys tem 10 ischaracterized by including a plural chamber diaphragm pump 101 wherein adiaphrragm 102 in common to first and second pumping chambers 103 and104 is connected through actuating linkage 105 with a rotary cam 106,the latter being fixed and driven to rotate with a shaft 108 at a speedwhich is directly proportional to the operating speed of the engine 17,and the actuating linkage 105 being adapted to drive the diaphragm 102at a rate which is directly proportional to the engine operating speedin response to rotation of the cam 106. A fuel tank 100, such as forgasoline, has a gravity feed line 109 communicating with the firstpumping chamber 103 through a one-way inlet valve 110 of the pump means,and there is a fuel outlet line 112 from the first pumping chamber incommunication with a one-way outlet valve 111 of the pump 101 andleading into the liquid fuel chambers 71 and 81 of the pressureresponsive flow control first and second valve means and 80 respectivelythrough the line branches 112a and 112!) for the pump 10] in response tooperation of the diaphragm 102 thereof to pump liquid fuel from the tank100 through the one-way inlet valve 110, the first pumping chamber 103and the oneway outlet valve 111, and through the outlet line 112 and itsbranches 112a and 112/1 and maintain pressure in the fuel chambers 71and 81 in the first and second flow control valve means 70 and 80. Aliquid fuel bleed-off line 117, bypassing the pumping chamber 103 andcommunicating with the liquid fuel outlet line 112 and with the liquidfuel inlet line 109, is equipped with a pressure responsive regulatingvalve 118 which opens in response to a predetermined maximum pressure inthe liquid fuel outlet line 112 for the bleed-off line 117 to returnliquid fuel received in the liquid fuel outlet line 112 from the firstpumping chamber 103 back to the liquid fuel inlet line 109 and thusalleviate pressure of liquid fuel in the liquid fuel chambers 71 and 81in the first and second flow control valve means 70 and 80 to be at apredetermined maximum pressure which assures having the valve outlets70b and 8012 normally closed by the valve needles 73 and 83. Further,the needle valve 73 carried on the diaphragm 74 and biased by the springis adapted to open the valve outlet port 70b in response to a decreasein static pressure brought about in the pressure chamber 72 by flow ofair induced by the engine 17 through the region of the passageway 16which is inside the venturi 90 for relatively open positions of thethrottle valve means 62 thus allowing liquid fuel in amounts increasingwith the engine operating speed above idling speed to issue from thevalve outlet port 70b until static pressure communicated from the regioninside the venturi 90 to the pressure chamber 72 once more increases forthe valve outlet port 70b to be closed. Liquid fuel issued from the flowcontrol first valve means 70 through the outlet port 70b when the latteris open passes through the passageway 16 into the reservoir means 15.When the throttle valve means 62 is relatively closed, the operation ofengine 17 causes a negative pressure to develop in the inductionmanifold 56 downstream of the throttle valve means 62 as well as in thepressure chamber 82 of the flow control second valve means and thispromotes movement of the valve needle 83 from a closed position to anopen position with reference to the valve outlet port 80b so as to haveliquid fuel on supply from the pump 101 flow through the outlet port 80band into the passageway for replenishing the bath 20. Under the latterconditions, static pressure in the region inside the venturi and in thepressure chamber 72 is increased due to reduced rate of intake of theengine 17 on lower operating speeds, having the throttle valve meansrelatively closed, and thus the outlet port 70b remains substantiallyclosed by the valve needle 73 until the throttle valve means 62 onceagain is brought to a relatively open position for static pressure todevelop in the pressure chamber 72 to promote opening of the outlet port70h while the outlet port 80b in the flow control second valve means 80remains substantially closed.

The second pumping chamber 104 in pump 101 is connected through aone-way inlet valve 121 with a liquid fuel inlet line 120 communicatingwith the opening 470 from the sump means 47 in the third liquid fuelextracting state means 45 and is connected through a one-way outletvalve 122 with a liquid fuel outlet line 123 which has an end 1234:inside the passageway upstream of the venturi 90 for liquid fuel to bereturned through the latter passageway from the sump means 47 to thebath of liquid fuel 20 inside the reservoir means 15 on operation of thepump diaphragm 102 at a rate varying in direct proportion to the speedof operation ofthe engine 17. In order to return liquid fuel from thesump means 42 in the second fuel extracting stage means 21b, a liquidfuel feed line 135 is introduced leading in the sump means 42 through anopening in the bottom portion of each of the partitions 37, and the feedline 135 has liquid fuel intake apertures 135a for communicating withliquid fuel in the sump means 42 at the bottom of each of the extractingchambers 31.. 32. 33, 34 and 35 and at the adjacent inner end of the airand fuel outlet duct means 13. A second venturi 136 formed as acomponent of the air inlet duct means 14 introduces a reduced openregion of the passageway 16 inside the second venturi 136 downstreamtoward the reservoir means 15 from the first venturi 90, and the feedline 135 has an open end 135/; disposed in the open region inside thesecond venturi 136. for air induced to flow through the passageway 16 onoperation of the engine 17 to develop a static pressure varyinginversely in intensity with velocity of air flow through the passageway16 in the environs of end 1351: and induce liquid to flow from the sumpmeans 42 through the feed line 135 from the apertures 135a and out theopen end 135/) and have fuel so issuing be returned through thepassageway 16 back into the reservoir means 15.

As the invention lends itself to many possible embodiments and as manypossible changes may be made in the embodiment hereinbefore set forth.it will be distinctly understood that all matter described herein is tobe interpreted as illustrative and not as a limitation.

I claim:

1. In an air and fuel mixing and feed system wherein an internalcombustion engine is equipped with throttle valve means and an inductionmanifold with said induction manifold intercommunicating downstream ofsaid throttle valve means with said throttle valve means and said enginefor said engine on negative pressure therein to take in a mixture of airand fuel from said induction manifold and be controlled by said throttlevalve means, the combination which includes: venturi and duct meanscomprising, air inlet duct means having a passageway therein and saidpassageway communicating with air ambient to said engine, and with saidthrottle valve means and said induction manifold through a bath ofliquid fuel normally contained in reservoir means of said system for amixture of air and fuel to be supplied to said engine in response tonegative pressure in said engine through said induction manifold andunder control of said throttle valve means. and venturi means having aninside open region for developing static pressure in said region varyinginversely in intensity with velocity of engine intake air flow inducedin said region by said engine; and means for pumping liquid fuel andregulating liquid fuel flow and pressure, the latter said meanscomprising. pump means for being operated with said engine at a rateincreasing and decreasing with operating speed of said engine forpumping liquid fuel. fuel flow regulator means including pressureresponsive flow control valve means having a pressure chambercommunicating with said region inside said venturi means and saidpressure responsive flow control valve means communicating with a liquidfuel pressurizing chamber in said pump means and with said reservoirmeans, for said pressure responsive flow control valve means to open inresponse to static pressure being decreased in said region inside saidventuri means and transmitted to said pressure chamber of said pressureresponsive flow control valve means for supplying said reservoir meanswith liquid fuel received from said pressurizing chamber of said pumpmeans, and for said pressure responsive flow control valve meanssubstantially to close when static pressure in said pressure chamber ofsaid pressure responsive flow control valve means is relatively high,and excess pressure alleviating means responsive to fluid pressurebeyond a predetermined maximum pressure and communicating for respondingto alleviate liquid fuel pressure in said pressurizing chamber of saidpump means.

2. In an air and fuel mixing and feed system set forth in claim 1wherein housing and duct means includes. a housing containing saidreservoir means with said air inlet duct means being in communicationwith air ambient to said engine and with said reservoir means in saidhousing, and air and fuel outlet duct means communicating with saidthrottle valve means and with said reservoir means, for air in responseto negative pressure in said engine to enter and flow through saidpassageway in said air inlet duct means into and through a bath ofliquid fuel in said reservoir means and pass carrying fuel through saidair and fuel outlet duct means in response to negative pressure in saidengine and under control of said throttle valve means.

3. In an air and fuel mixing and feed system as set forth in claim 2wherein said air and fuel outlet means is controlled to be opened andclosed by one-way check valve means opening said air and fuel outletmeans in response to flow of air carrying fuel being induced from saidinduction manifold on operation of said engine and closing said air andfuel outlet means in response to pressure of backfire of said engine.and backfire pressure relief valve means is provided communicating withsaid air and fuel outlet means downstream of said one-way check valvemeans for relieving pressure of backfire of said engine having saidone-way check valve means closed.

4. ln an air and fuel mixing and feed system as set forth in claim 2wherein said system is characterized by including filter means disposedfor extracting liquid fuel from an air and fuel mixture passing en routeto said engine from said reservoir means.

5. In an air and fuel mixing and feed sytem as set forth in claim 2wherein said system is characterized by including extractor meanscomprising filter means and sump means disposed between said reservoirmeans and said induction manifold for said filter means to extractliquid fuel from an air and fuel mixture passing en route to said enginefrom a bath of liquid fuel normally in said reservoir means and saidsump means to collect liquid fuel from said filter means, and said pumpmeans communicates with said sump means and with said reservoir meansfor fuel from said sump means to bereturned to said reservoir means onoperation of said pump means 6. In an air and fuel mixing and feedsystem as set forth in claim 2 wherein said system is characterized byincluding filter means disposed in said housing between said reservoirmeans and said induction manifold for extracting liquid fuel from an airand fuel mixture passing en route to said induction manifold from a bathof liquid fuel normally contained in said reservoir means.

7. In an air and fuel mixing and feed system as set forth in claim 2wherein said system is characterized by including labyrinthic passagemeans disposed in said housing between said reservoir means and saidinduction manifold, and said labyrinthic passage means contains filtermeans for extracting liquid fuel from an air and fuel mixture passingthrough said labyrinthic passage means cn route to said inductionmanifold from a hath of liquid fuel normally contained in said reservoirmeans.

8. In an air and fuel mixing and feed system as set forth in claim 2wherein said system is characterized by including extractor meanscomprising filter means and sump means disposed in said housing betweensaid reservoir means and said induction manifold for said filter meansto extract liquid fuel from a fuel and air mixture passing en route tosaid induction manifold from a bath of liquid fuel normally contained insaid reservoir means, and said sump means communicates with saidreservoir means for liquid fuel in said sump means to be returned tosaidreservoir means.

9. In an air and fuel mixing and feed system as set forth in claim 8wherein said venturi and duct means includes said venturi meansintercommunicating with second venturi means through an intermediateportion of said passageway in said duct means, and there being a feedline having feed line inlet means communicating with said sump means andhaving feed line outlet means in an open region inside said secondventuri means for static pressure varying inversely in intensity withvelocity of air flowing through said region inside said second venturimeans to develop in said region inside said second venturi means andinduce fuel from said sump means to flow in said feed line from saidfeed line inlet means to said feed line outlet means.

10. In an air and fuel mixing and feed system as set forth in claim 9wherein said system is characterized by said extractor means includingsupplemental filter means and supplemental sump means interposed betweensaid housing and said induction manifold for said supplemental filtermeans to extract liquid fuel from a fuel and air mixture passing enroute to said engine from a bath of liquid fuel normally in saidreservoir means and said supplemental sump means to collect liquid fuelfrom said supplemental filter means, and said pump means communicateswith said reservoir means for inducing fuel to flow from saidsupplemental sump means and be returned to said reservoir means.

11. In an air and fuel mixing and feed system as set forth in claim 1wherein said system is characterized by including filter means and sumpmeans, said filter means for extracting liquid fuel from an air and fuelmixture passing en route to said induction manifold from a bath ofliquid fuel normally contained in said reservoir means and said sumpmeans to collect liquid fuel from said filter means, and said pump meanscommunicating with said sump means and with said reservoir means forinducing fuel to flow from said sump means and be returned to saidreservoir means.

12. In an air and fuel mixing and feed system as set forth in claim 1wherein said venturi and duct means includes said venturi meansi'ntercommunicating with second venturi means through an intermediateportion of said passageway in said air inlet duct means, and said systemis further characterized by including filter means and sump means, saidfilter means for extracting liquid fuel from an air and fuel mixturepassing en route to said induction manifold from a bath of liquid fuelnormally contained in said reservoir means and said sump means tocollect liquid fuel from said filter means. and there being a feed linehaving feed line inlet means communicating with said sump means andhaving feed line outlet means in an open region inside said secondventuri means for static pressure varying inversely with velocity of airflowing through said region inside said second venturi means to developin said region inside said second venturi means and induce fuel fromsaid sump means to flow in said feed line from said feed line inletmeans to said feed line outlet means.

13. In an air and fuel mixing and feed system wherein an internalcombustion engine is equipped with throttle valve means and an inductionmanifold with said induction manifold intercommunicating downstream ofsaid throttle valve means with said throttle valve means and said enginefor said engine on negative pressure therein to take in a mixture of airand fuel from said induction manifold and be controlled by said throttlevalve means, the combination which includes; venturi and duct meanscomprising, air inlet duct means having a passageway therein and saidpassageway communicating with air ambient to said engine, and with saidthrottle valve means and said induction manifold through a bath ofliquid fuel normally contained in reservoir means of said system for amixture of air and fuel to be supplied to said engine in response tonegative pressure in said engine through said induction manifold undercontrol of said throttle valve means, and venturi means having an insideopen region for developing static pressure in said region varyinginversely in intensity with velocity ofenginc intake air flow induced insaid region by said engine; and means for pumping liquid fuel andregulating liquid fuel flow and pressure, the latter said meanscomprising, pump means for being operated with said engine at a rateincreasing and decreasing with operating speed of said engine forpumping liquid fuel, fuel flow regulator means including pressureresponsive flow control first valve means having a first pressurechamber communicating with said region inside said venturi means andsaid flow control first valve means communicating with said pump meansand with said reservoir means, for said flow control first valve meansto open to an increasing degree in response to static pressure beingdecreased and transmitted from said region inside said venturi means tosaid first pressure chamber for supplying said reservoir means withliquid fuel received from said pump means as said throttle valve meansis progressively opened and substantially closed in response torelatively high static pressure transmitted from said region inside saidventuri means to said first pressure chamber when said throttle valvemeans is in a relatively closed position and pressure responsive flowcontrol second valve means having a second pressure chambercommunicating with said induction manifold downstream of said throttlevalve means and pressure responsive flow control second valve meanscommunicating with said pump means and said reservoir means for saidpressure responsive flow control second valve'means to open forsupplying said reservoir means with liquid fuel from said pump means inresponse to low pressure developed between said throttle valve and saidengine having said throttle valve means in said relatively closedposition and for said pressure responsive flow control second valvemeans substantially to close in response to relatively high pressuredeveloped between said throttle valve means and said engine as saidthrottle valve means is opened, and excess pressure alleviating meansresponsive to fluid pressure beyond a predetermined maximum pressure andcommunicating for responding to alleviate liquid fuel output pressure ofsaid pump means.

14. In an air and fuel mixing and feed system as set forth in claim 13wherein said system is characterized by including extractor meanscomprising filter means and sump means, said filter means for extractingliquid fuel from an air and fuel mixture passing en route to saidinduction manifold from a bath of liquid fuel normally in said reservoirmeans and said sump means to collect liquid fuel from said filter means,and said pump means including first and second pressurizing chambers forpumping liquid fuel, said first pressurizing chamber communicating withsaid pressure responsive flow control first and second valve means forliquid fuel pressurized in said first pressurizing chamber to besupplied through said pressure responsive flow control first and secondvalve means as controlled and thence to said reservoir means, and saidsecond pressurizing chamber communicating with said sump means and withsaid reservoir means for fuel from said sump means to be returned tosaid reservoir means,

15. In an air and fuel mixing and feed system as set forth in claim 13wherein said venturi and duct means includes said venturi meansintercommunicating with second venturi means through an intermediateportion of said passageway in said air inlet duct means, and said systemis further characterized by including extractor means comprising filtermeans and sump means, said filter means for extracting liquid fuel froma fuel and air mixture passing en route to said induction manifold froma bath of liquid fuel normally in said reservoir means and said sumpmeans to collect liquid fuel from said filter means, and there being afeed line having feed line inlet means communicating with said sumpmeans and having feed line outlet means in an open region inside saidsecond venturi means for static pressure varying inversely in intensitywith velocity of air flowing through said region inside said secondventuri means to develop in said region inside said second venturi meansand induce fuel from said sump means to flow in said feed line from saidfeed line inlet means to said feed line outlet means.

1. In an air and fuel mixing and feed system wherein an internalcombustion engine is equipped with throttle valve means and an inductionmanifold with said induction manifold intercommunicating downstream ofsaid throttle valve means with said throttle valve means and said enginefor said engine on negative pressure therein to take in a mixture of airand fuel from said induction manifold and be controlled by said throttlevalve means, the combination which includes; venturi and duct meanscomprising, air inlet duct means having a passageway therein and saidpassageway communicating with air ambient to said engine, and with saidthrottle valve means and said induction manifold through a bath ofliquid fuel normally contained in reservoir means of said system for amixture of air and fuel to be supplied to said engine in response tonegative pressure in said engine through said induction manifold andunder control of said throttle valve means, and venturi means having aninside open region for developing static pressure in said region varyinginversely in intensity with velocity of engine intake air flow inducedin said region by said engine; and means for pumping liquid fuel andregulating liquid fuel flow and pressure, the latter said meanscomprising, pump means for being operated with said engine at a rateincreasing and decreasing with operating speed of said engine forpumping liquid fuel, fuel flow regulator means including pressureresponsive flow control valve means having a pressure chambercommunicating with said region inside said venturi means and saidpressure responsive flow control valve means communicating with a liquidfuel pressurizing chamber in said pump means and with said reservoirmeans, for said pressure responsive flow control valve means to open inresponse to static pressure being decreased in said region inside saidventuri means and transmitted to said pressure chamber of said pressureresponsive flow control valve means for supplying said reservoir meanswith liquid fuel received from said pressurizing chamber of said pumpmeans, and for said pressure responsive flow control valve meanssubstantially to close when static pressure in said pressure chamber ofsaid pressure responsive flow control valve means is relatively high,and excess pressure alleviating means responsive to fluid pressurebeyond a predetermined maximum pressure and communicating for respondingto alleviate liquid fuel pressure in said pressurizing chamber of saidpump means.
 2. In an air and fuel mixing and feed system as set forth inclaim 1 wherein housing and duct means includes, a housing containingsaid reservoir means with said air inlet duct means being incommunication with air ambient to said engine and with said reservoirmeans in said housing, and air and fuel outlet duct means communicatingwith said throttle valve means and with said reservoir means, for air inresponse to negative pressure in said engine to enter and flow throughsaid passageway in said air inlet duct means into and through a bath ofliquid fuel in said reservoir means and pass carrying fuel through saidair and fuel outlet duct means in response to negative pressure in saidengine and under control of said throttle valve means.
 3. In an air andfuel mixing and feed system as set forth in claim 2 wherein said air andfuel outlet means is controlled to be opened and closed by one-way checkvalve means opening said air and fuel outlet means in response to flowof air carrying fuel being induced from said induction manifold onoperation of said engine and closing said air and fuel outlet means inresponse to pressure of backfire of said engine, and backfire pressurerelief valve means is provided communicating with said air and fueloutlet means downstream of said one-way check valve means for relievingpressure of backfire of said engine having said one-way check valvemeans closed.
 4. In an air and fuel mixing and feed system as set forthin claim 2 wherein said system is characterized by including filtermeans disposed for extracting liquid fuel from an air and fuel mixturepassing en route to said engine from said reservoir means.
 5. In an airand fuel mixing and feed sytem as set forth in claim 2 wherein saidsystem is characterized by including extractor means comprising filtermeans and sump means disposed between said reservoir means and saidinduction manifold for said filter means to extract liquid fuel from anair and fuel mixture passing en route to said engine from a bath ofliquid fuel normally in said reservoir means and said sump means tocollect liquid fuel from said filter means, and said pump meanscommunicates with said sump means and with said reservoir means for fuelfrom said sump means to be returned to said reservoir means on operationof said pump means.
 6. In an air and fuel mixing and feed system as setforth in claim 2 wherein said system is characterized by includingfilter means disposed in said housing between said reservoir means andsaid induction manifold for extracting liquid fuel from an air and fuelmixture passing en route to said induction manifold from a bath ofliquid fuel normally contained in said reservoir means.
 7. In an air andfuel mixing and feed system as set forth in claim 2 wherein said systemis characterized by including labyrinthic passage means disposed in saidhousing between said reservoir means and said induction manifold, andsaid labyrinthic passage means contains filter means for extractingliquid fuel from an air and fuel mixture passing through saidlabyrinthic passage means en route to said induction manifold from abath of liquid fuel normally contained in said reservoir means.
 8. In anair and fuel mixing and feed system as set forth in claim 2 wherein saidsystem is characterized by including extractor means comprising filtermeans and sump means disposed in said housing between said reservoirmeans and said induction manifold for said filter means to extractliquid fuel from a fuel and air mixture passing en route to saidinduction manifold from a bath of liquid fuel normally contained in saidreservoir means, and said sump means communicates with said reservoirmeans for liquid fuel in said sump means to be returned to saidreservoir means.
 9. In an air and fuel mixing and feed system as setforth in claim 8 wherein said venturi and duct means includes saidventuri means intercommunicating with second ventUri means through anintermediate portion of said passageway in said duct means, and therebeing a feed line having feed line inlet means communicating with saidsump means and having feed line outlet means in an open region insidesaid second venturi means for static pressure varying inversely inintensity with velocity of air flowing through said region inside saidsecond venturi means to develop in said region inside said secondventuri means and induce fuel from said sump means to flow in said feedline from said feed line inlet means to said feed line outlet means. 10.In an air and fuel mixing and feed system as set forth in claim 9wherein said system is characterized by said extractor means includingsupplemental filter means and supplemental sump means interposed betweensaid housing and said induction manifold for said supplemental filtermeans to extract liquid fuel from a fuel and air mixture passing enroute to said engine from a bath of liquid fuel normally in saidreservoir means and said supplemental sump means to collect liquid fuelfrom said supplemental filter means, and said pump means communicateswith said reservoir means for inducing fuel to flow from saidsupplemental sump means and be returned to said reservoir means.
 11. Inan air and fuel mixing and feed system as set forth in claim 1 whereinsaid system is characterized by including filter means and sump means,said filter means for extracting liquid fuel from an air and fuelmixture passing en route to said induction manifold from a bath ofliquid fuel normally contained in said reservoir means and said sumpmeans to collect liquid fuel from said filter means, and said pump meanscommunicating with said sump means and with said reservoir means forinducing fuel to flow from said sump means and be returned to saidreservoir means.
 12. In an air and fuel mixing and feed system as setforth in claim 1 wherein said venturi and duct means includes saidventuri means intercommunicating with second venturi means through anintermediate portion of said passageway in said air inlet duct means,and said system is further characterized by including filter means andsump means, said filter means for extracting liquid fuel from an air andfuel mixture passing en route to said induction manifold from a bath ofliquid fuel normally contained in said reservoir means and said sumpmeans to collect liquid fuel from said filter means, and there being afeed line having feed line inlet means communicating with said sumpmeans and having feed line outlet means in an open region inside saidsecond venturi means for static pressure varying inversely with velocityof air flowing through said region inside said second venturi means todevelop in said region inside said second venturi means and induce fuelfrom said sump means to flow in said feed line from said feed line inletmeans to said feed line outlet means.
 13. In an air and fuel mixing andfeed system wherein an internal combustion engine is equipped withthrottle valve means and an induction manifold with said inductionmanifold intercommunicating downstream of said throttle valve means withsaid throttle valve means and said engine for said engine on negativepressure therein to take in a mixture of air and fuel from saidinduction manifold and be controlled by said throttle valve means, thecombination which includes; venturi and duct means comprising, air inletduct means having a passageway therein and said passageway communicatingwith air ambient to said engine, and with said throttle valve means andsaid induction manifold through a bath of liquid fuel normally containedin reservoir means of said system for a mixture of air and fuel to besupplied to said engine in response to negative pressure in said enginethrough said induction manifold under control of said throttle valvemeans, and venturi means having an inside open region for developingstatic pressure in said region varying inversely in intensity withvelocity of engine intake air flow induCed in said region by saidengine; and means for pumping liquid fuel and regulating liquid fuelflow and pressure, the latter said means comprising, pump means forbeing operated with said engine at a rate increasing and decreasing withoperating speed of said engine for pumping liquid fuel, fuel flowregulator means including pressure responsive flow control first valvemeans having a first pressure chamber communicating with said regioninside said venturi means and said flow control first valve meanscommunicating with said pump means and with said reservoir means, forsaid flow control first valve means to open to an increasing degree inresponse to static pressure being decreased and transmitted from saidregion inside said venturi means to said first pressure chamber forsupplying said reservoir means with liquid fuel received from said pumpmeans as said throttle valve means is progressively opened andsubstantially closed in response to relatively high static pressuretransmitted from said region inside said venturi means to said firstpressure chamber when said throttle valve means is in a relativelyclosed position and pressure responsive flow control second valve meanshaving a second pressure chamber communicating with said inductionmanifold downstream of said throttle valve means and pressure responsiveflow control second valve means communicating with said pump means andsaid reservoir means for said pressure responsive flow control secondvalve means to open for supplying said reservoir means with liquid fuelfrom said pump means in response to low pressure developed between saidthrottle valve and said engine having said throttle valve means in saidrelatively closed position and for said pressure responsive flow controlsecond valve means substantially to close in response to relatively highpressure developed between said throttle valve means and said engine assaid throttle valve means is opened, and excess pressure alleviatingmeans responsive to fluid pressure beyond a predetermined maximumpressure and communicating for responding to alleviate liquid fueloutput pressure of said pump means.
 14. In an air and fuel mixing andfeed system as set forth in claim 13 wherein said system ischaracterized by including extractor means comprising filter means andsump means, said filter means for extracting liquid fuel from an air andfuel mixture passing en route to said induction manifold from a bath ofliquid fuel normally in said reservoir means and said sump means tocollect liquid fuel from said filter means, and said pump meansincluding first and second pressurizing chambers for pumping liquidfuel, said first pressurizing chamber communicating with said pressureresponsive flow control first and second valve means for liquid fuelpressurized in said first pressurizing chamber to be supplied throughsaid pressure responsive flow control first and second valve means ascontrolled and thence to said reservoir means, and said secondpressurizing chamber communicating with said sump means and with saidreservoir means for fuel from said sump means to be returned to saidreservoir means.
 15. In an air and fuel mixing and feed system as setforth in claim 13 wherein said venturi and duct means includes saidventuri means intercommunicating with second venturi means through anintermediate portion of said passageway in said air inlet duct means,and said system is further characterized by including extractor meanscomprising filter means and sump means, said filter means for extractingliquid fuel from a fuel and air mixture passing en route to saidinduction manifold from a bath of liquid fuel normally in said reservoirmeans and said sump means to collect liquid fuel from said filter means,and there being a feed line having feed line inlet means communicatingwith said sump means and having feed line outlet means in an open regioninside said second venturi means for static pressure varying inverselyin intensity with velocity of air flowing through said regiOn insidesaid second venturi means to develop in said region inside said secondventuri means and induce fuel from said sump means to flow in said feedline from said feed line inlet means to said feed line outlet means.